LOS ANGELES (Reuters) – The windfall gains from the tax cuts passed by the U.S. Congress in December have brought back “animal spirits” that encourage risk-taking throughout corporate America, according to some of the participants at the annual Milken Institute Global Conference in California on Monday.

“Tax reform in the United States has led to, frankly, a number of companies flush with cash and looking for their opportunity to use their balance sheets to affect significant change in their market places as exhibited by two of the big mergers in telecom and energy announced” in the last 24 hours, Robert Smith, founder and CEO of private equity firm Vista Equity Partners, said at a panel discussion.

Late Sunday, T-Mobile US Inc and Sprint Corp said they had agreed to a $26 billion all-stock merger and believed they could win over skeptical U.S. regulators because the merger would create thousands of jobs and help the United States beat China in creating the 5G next generation mobile phone network.

Also on Monday, Marathon Petroleum Corp agreed to buy rival Andeavor for more than $23 billion in the largest-ever tie-up between U.S. oil refiners, giving the combined company a nationwide presence and increased access to growing export markets.

Michael Corbat, the chief executive officer of Citigroup Inc, was also positive about the economic outlook and said the Trump tax cuts have yet to filter through to many businesses.

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“The benefits of tax reform aren’t yet fully into our economy. Not yet fully appreciated in terms of the intermediate impact they can have,” he said.

U.S. Representative Kevin McCarthy, the leader of the Republican-majority in the House, said the tax cut bill has been a huge boost for Americans.

“We’ve watched the growth of America expand. People are talking about 3.0 percent growth, we haven’t seen that in quite some time,” McCarthy said, adding that Americans have received pay raises and bonuses.

However, rapidly changing technology is providing challenges for many U.S. businesses and may be driving populist political policies which are undermining the business confidence generated by the U.S. tax cuts, conference speakers said.

Jim McCaughan, chief executive officer at Principal Global Investors, said technological advances are resulting in poor job prospects for some of the world’s population, but politicians are in denial about this and are mistakenly blaming immigration and free trade. As result, the onus is on business leaders to re-train workers, he said.

People “feel angry in part because the reason for their displacement and the lack of good job prospects isn’t the foreigner, the trade, the immigrant, it’s actually technology. And that is why re-skilling is so important”, he said.

One example of the uncertainty created for U.S. business by misplaced policies is President Trump’s tariffs on imported steel and aluminum. The exemptions from the tariffs for some countries expire on Tuesday, but it was still not clear on Monday which U.S. allies would get their exemptions renewed.

The uncertainty resulting from technological changes is also making it hard for chief executives to plan ahead, Vista’s Smith added.

“It’s pretty reasonable to project a strategy for the next 12 months but frankly when you start talking about three to five years, it gets really murky really fast,” he said.

“CEOs are expected to not only understand technologies that didn’t exist one or two years ago but to make strategic decisions as to which investments to make, and the pace of these changes have staggering consequences if you get it wrong,” he said.

“The CEOs I talk to have never been more excited and never been more paranoid at the same time,” Smith said.

Another concern for businesses is rising U.S. interest rates.

Scott Minerd, global chief investment officer at Guggenheim Partners, warned that Trump’s tax cuts could trigger more interest rate hikes by the Federal Reserve. “We are coming in the United States to a point where the stimulus and fiscal policy put in place in Washington is colliding with monetary policy.”